English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The proximity effect (PE) of QSOs is believed to be useful in constrainingthe QSO lifetime. Observations on the PE so far, however, give apparentlycontradictory results -- some are consistent with a long QSO lifetime (>~ a few10^7 yr), but others appear to be only consistent with a short QSO lifetime <~10^6 yr. In this paper, we show that this apparent contradiction may be solvedby simultaneously taking into account both the effect due to the densityenhancement in the QSO near zones and that due to the obscuration of the toriassociated with the QSOs, using a large number of Monte-Carlo generatedsynthetic Lyman alpha forest spectra. We demonstrate that the QSO propertiesand environment can be constrained simultaneously by the transverse PE and theline of sight PE of bright type 1 QSOs together. The current availablemeasurements on the PEs of type 1 QSOs suggest that (1) the density issignificantly enhanced in the vicinity of the QSOs; (2) the QSO lifetime isconsistent with being as large as a few 10^7 yr and a substantially shorterlifetime (e.g., <~10^6 yr) is not required; and (3) the half opening angle ofthe tori associated with QSOs is ~60 deg, consistent with some otherindependent estimates. Our simulations also show that the TPE of type 2 QSOscan be significantly different from that of type 1 QSOs, which may be useful toput further constraints on the QSO properties and the QSO environment.

On probing the properties of QSOs through their proximity effects on the intergalactic medium